INDEX. 567 



PAGE 



Arid and humid climates, rock-weathering in 47 



Arid and humid regions, criteria of soils of 371 



contrast between soils of 28 



soils of iu ) 37I 



Arid and humid soils, general comparison ; table 375, 377 



Arid belts, subtropic 298, 299 



utilization of 299 



Arid conditions, local, in tropical countries 401 



Aridity, inflnence upon civilization 417 



Arid region, bunch grasses on soils of in 



standing hay in 300 



upland soils of ; table 373, 374 



Arid soils, productiveness induces permanent civil organization 412 



Arroyo Grande and Yazoo buckshot soils 345 



Asparagus, resistant to salts 475 



Atmosphere, composition of ; table , 16 



Azotobacter 156 



Lipman on , 156 



B. 



Bacteria, active in soil -formation 20 



aerobic and anaerobic 144 



denitrifying 148 



food and functions of 145 



in soils, numbers of .... 142 



micro-organisms of soils 142 



multiplication of 144 



nitrifying 146 



Bacterial life, effect on soil, condition 149 



relation of carbonic dioxid to 281 



Bacteroids . . 151 



Mork figures 152, 153 



Basaltic rocks 49 



Basalts, red soils from 52 



Basic slag 64 



Basin irrigation, advantages of 243 



Bauxite in soils 101,390 



Beet, sugar, effects of salts on 474 



tolerant of common salt 474 



Bhilsoils 4 J 4 



Bicarbonate of soda 78 



Black-alkali lands, difficulty in draining 462 



neutralizing of 457 



waters, use of 250 



why so called 7^ 



Black earth of Russia, humus in ; table 130 



Black sand. . 45 



